How's that for a Haiku? I have a Gigavac SPDT relay rated for 1300 V DC which I use for both precharge and discharge. I'd really like to just leave it permanently across the contactor, but the race rules state that I need to be able to discharge the potential in the capacitors as well. So an affordable relay could be a winner!

As an alternative 817-FTR-J2AK012W is max rated at 600VDC for $16.78
Or 2 in series would be $33.56 and 1200V.
They are 24 x 24mm and 27mm High
So a little bit bigger in footprint but a truck load cheaper.
And at 10A is probably still suitable for precharge etc...

Discharge: A big high value resistor permanently across the caps?
Say a trickle current of 1mA, so will discharge a 1000uF/600V cap in 10 minutes or so. Or use the motor controller to discharge the cap into the motor windings really quickly.

For many applications, is there a reason that an isolation DC-DC onto an IBGT or MOSFET and resistor couldn't be used for precharge or discharge purposes?

A 50 amp precharge driver should cost about $50 with the following key parts:

It really depends on how the system is setup.
I don't see a problem with discharge being an IGBT as this in in the controller and isolated by contactors.
But precharge is a bit different as this needs to bypass a main contactor.
If it was in the battery pack it could "leak" out on to the main line even when not connected to a controller.
If it was in the controller it could "leak" back on to the main line until the discharge removes the charge from the caps.

Still in my opinion the leakage current from an IGBT is small enough that a small string of resistors can load up the leakage so the output voltage is too low to be an issue.

The real issue will be if it is still safe when something goes wrong...

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